As an input medium, the touch screen is currently a most simple, convenient and natural way of man-machine interaction. It has been a research focus to integrate touch function into a display device for more and more flat-panel displayer manufacturers.
At present, capacitive touch is a widely adopted touch technique. In order to reduce thickness of a display panel and achieve touch function, usually a touch structure is integrated into the display panel. A plurality of touch electrodes is formed at the display area, a common electrode for displaying a pixel can also be used as a touch electrode and be driven by time division. During a display stage, the common electrode receives a common signal, and during a touch stage, the common electrode receives a touch signal. In the prior art, the signal of the common electrode used as the touch electrode is transmitted via a metal line arranged in a different layer. An insulation layer is provided between the metal line and the electrode, and an electrical connection is achieved by punching a hole, since the punching position is limited by the shape and arrangement of electrode, the through hole is usually distributed non-uniformly, resulting in that the through hole is visible, thereby forming a display mura, which influences display effect of the touch display panel. In the prior art, in order to solve such a problem, a dummy signal line is provided so as to provide a dummy through hole thereon, then by adjusting distribution of the through hole, so that an uniform distribution of the through hole can be achieved to solve the problem of display mura. However, the dummy signal line is not adaptive to all built-in touch structures, for example, a structure in which the touch signal line and a specific metal layer are arranged in a same layer, there is no enough space for arranging the dummy signal line, so that the problem of display mura caused by non-uniform distribution of the through hole cannot be solved.